Interference occurring due to transmissions sent from/to neighbor satellites, using the same frequencies as well as interference occurring due to communications transmitted along satellites beams using the same frequencies, tend to degrade the reception performance and to limit the maximal channel throughput.
Interference to communications exchanged along satellite links is one of the major factors limiting the capacity of satellite communication. Modern satellites include numerous transponders transmitting at different frequencies, different antennas (single beam or multiple beam), and different polarizations per antenna. Thus, a ground receiver of a satellite link is susceptible to interference that may arise, for example, from co-frequency transmissions at the same frequency, same beam but different polarization (co-frequency, co-beam, cross polarization), same frequency but a different beam (co-frequency, adjacent beam), and adjacent frequency channel from the same or from different beams.
As the satellite uplink receiver is also susceptible to interference, interference on the uplink may leak into the desired channel as well. Additionally, unwanted interference originating from an adjacent satellite may also occur as well as interfering signals from terrestrial sources.
Interference events may be caused by rules violations or errors made by operators. However, the effects of these events might be mitigated due to the newly established Carrier ID standard, which enables a satellite operator or regulators to identify and shut down interfering transmissions. Nevertheless, even links that operate in accordance with the operation rules and regulations may still be a source of interference.
Active interference cancellation means are available. Such means typically involve building a dedicated receiver to capture the interfering signal and then cancel it by subtraction from the wanted signal. Obviously, this technique is rather costly while perfect cancellation is never possible. Even when the interfering signal is known (which is the case when dummy frames are transmitted), cancellation requires synchronization and channel estimation of the interference, which might still require installation of additional circuitry.